Terminology:
Poltergeist is a very rarely observed anomalous event. It shows as unexplained and even absurd effects of affection on different objects, including living.
Poltergeist events have some common "style" of loose, independently on place or time of phenomena. Mostly it is possible to trace the connection of the phenomena with a human being, who is kind of standing in the focus of the event, and who is often called the "bearer of poltergeist" in the literature. Besides, studies of last poltergeist events in Estonia and analysis of materials about other poltergeist activity, it is easy to come to conclusion that besides the "bearer of poltergeist", there is at least one more, alive or dead, human being, which interacts with a "bearer".

Examples:
Poltergeist in Kunda
Poltergeist in Kallavere
Poltergeist on Videviku street, Tallinn
Poltergeist on Ümera street, Tallinn
Poltergeist in Kohtla-Järve

History:
Poltergeists are evenly distributed in time and territory. On Earth, it is spread from China to Peru. Written evidences of poltergeist events are known in different cultures and met throughout the centuries, up to the most ancient of known states of human society. There is a known letter, which has been written by Egyptian scribe by the request of one man, whose house became "restless" after his wife died. The letter is addressed to her (wife) and expresses confusion and reproaches, because life in such "restless" home became very tiresome.
There were some cases of stone-throwing poltergeist in years 355, 530, 1138 and 1170. In year 335, there was the case of invisible force in Biegen-am-Rhein, which was throwing stones, kicked sleeping people from their beds, knocked, cracked and drummed on the streets. Since then, such events occurred all over the world.
Here is the description of the ‘stone-throwing’ poltergeist happened nowadays, in 1982 in Ivory Coast (West Africa): The "stonefall" marred the peace of life of one small village. It was accompanied with "bottlefall" and "woodfall". These real heavy "shells" were flying to and fro and injured lots of people. One of the first injured was Madame Mary-Rose Akissi Yao. The stone hit her head and she fell on the floor, while she was in her hut. She recalled that "… stones where flying everywhere in the village and it has been very scary. The smash of falling stones was ringing in the ears. Everybody was in panic." Adjua Yao told, "I don’t know where the stones were flying from. One of them hit my neck. The hit was so strong that I lost consciousness." People were convinced that some invisible enemy has began the war against them. They appealed to local authorities and voodoos asking to do something about it. But African savannas’ authorities and magicians were powerless, as well as our local ones, who had to deal with this kind of things, as we will see later in the examples.
The famous parapsychologist Hereward Carrington has described and thoroughly analyzed 375 cases of poltergeist from year 355 till 1949. Unmasking 26 examples of clear scam and discrediting 19 more doubtful stories, he has come to the conclusion that the rest 330 cases are real and cannot be explained by an affection by any known factor.

Hypotheses:
Religious hypotheses ("demons", "devil")
Mythical species ("evil spirit", "bogy")
Occultist hypothesis of spontaneous reflexive psychokinesis ("spirits", "soul")
Hypothesis of unprompted telekinesis
Hypothesis of an invisible man
Hypothesis of "superman"
Hypothesis of actions of people from future by means of "time machine"
Hypothesis of prank arranged by hosts in order to attract attention or connected to any other interests like moving to another apartment
Hypothesis of children’s frolic
Hypothesis of psychic or mental disorder
Hypothesis of collective psychosis and collective hallucinations
Hypothesis of remote hypnosis
Hypothesis of joint actions of group of very skilful paraphsychologists or occultists
Hypothesis of ideological sabotage
Hypothesis of total zombying of population
Hypothesis of psychological preparing of humanity to contacts with supreme civilizations
Hypothesis of showing possibilities of supreme civilizations
Hypothesis of control of physical affection by supreme civilizations
Hypothesis of psychological test carried out by supreme civilizations